Providing an adequate supply of lubricant from the lubrication system of an internal combustion engine to the valves and the bearing surfaces of the rocker arm assemblies has long been a concern of engine manufacturers. It is vitally important that the bearing surfaces be properly lubricated. Unless the proper amount of lubricant is supplied to the rocker arm bearing surfaces, the valve stems and the push rod, these parts will not be able to maintain the constant motion required of them during engine operation, but will tend to stick and, ultimately, could become frozen and immovable. If the rocker arm bearing surface does not receive adequate lubrication, the bearing surfaces rapidly overheat, thereby totally sealing out any lubricant available for these bearing surfaces and rapidly destroying them through heat, friction and galling action.
Conversely, if too much lubricant is supplied to the rocker arms, valves and push rods, an excess load will be placed on the lubricant pump and lead to an unnecessary parasitic load on the engine with concommitant loss in engine efficiency. Since lubricant is generally supplied to the rocker arms under pressure, an excessive amount of lubricant could accumulate in the vicinity of the engine head.
An ideal rocker assembly lubricant supply line is one that is simple in configuration, has only a minimum number of parts, is easy to install during engine assembly and provides an automatic fluid connection between the rocker assemblies and the engine lubrication fluid circuit. An ideal lubricant supply line will also be inexpensive to manufacture and easy to replace.
The prior art has proposed various solutions for addressing the problem of providing and maintaining an adequate flow of lubricant to the rocker arm bearing surfaces, valve stems and push rods. Some type of fluid connection between the engine lubrication circuit and each rocker assembly with its associated valves and push rods must be provided to convey lubricant from the lubrication circuit to the rocker assemblies. U.S. Pat. No. 2,641,235 to Slonneger is exemplary of the prior art which provides a direct fluid connection between the crankcase and each rocker assembly by a series of conduits contained within the block and the head. Lubricant is supplied directly to the base of the rocker arm support by a duct in the head. This arrangement, however, requires a multiplicity of lubricant supply lines and ducts for each rocker assembly, all of which have to be installed separately during engine assembly. Moreover, the appropriate ducts have to be formed during casting or subsequently bored in the engine head in specific locations for each rocker assembly, causing substantial manufacturing expense.
Another solution to the rocker assembly lubrication supply problem directs lubricant directly to the shaft on which the rocker arms are journaled as disclosed in U.S. Pat. No. 1,363,500 by Duesenberg et al. Lubricant can then be directly communicated to the bearing surfaces from the crankcase. The arrangement taught by Duesenberg et al, however, requires an exteriorly located lubricant supply pipe from the sump to the rocker assembly bearing shaft which includes bores to correspond with each rocker assembly. While the installation of this type of lubrication supply line has fewer components to manufacture and assemble than the type of lubricant supply system described by Slonneger, the connection of the exterior supply line represents a separate installation step from the assembly of the rocker arm support.
Lubrication of the valve stems has also been achieved by providing lubricant supply lines positioned above the valves and supported by the rocker cover. U.S. Pat. No. 1,438,163 to Montgomery discloses a forced feed oiler which extends along a longitudinal axis inside the rocker cover and includes a plurality of depending tubes extending downwardly toward the rocker assembly. The tubes terminate in wicks which are held in operative relationship with the parts to be lubricated. A similar wick-type rocker arm lubricator is disclosed in U.S. Pat. No. 1,491,710 to Layman, except that the lubricant supply lines are located outside the rocker cover. This lubricator also employs a number of downwardly directed pipes and wicks to convey lubricant to the rocker arms and bearings. A similar arrangement is additionally taught by Bijur in U.S. Pat. No. 2,104,729. In this patent, lubrication is supplied to the rocker assemblies by a multi-part circuit which is mounted completely exteriorly to the rocker cover and provides a direct connection to meter lubricant to each pair of rocker arms and associated structures. While all of the lubricant supply systems described in the aforementioned references may effectively supply lubricant to the rocker arms and associated structures, the number of component parts of each of these systems make such systems expensive to manufacture, difficult to assemble and install quickly during engine assembly and prone to leaking and other problems after installation.
Consequently, the prior art has failed to disclose a simple, inexpensive lubricant supply system which may be quickly and easily installed during engine assembly to provide automatic controlled fluid communication between the engine lubrication circuit and a plurality of rocker arm assemblies and which may be quickly and easily replaced, if required, during engine maintenance.